Re: 2nd Level Buffer Cache

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "PG Hackers" <pgsql-hackers(at)postgresql(dot)org>, Rados*aw Smogura <rsmogura(at)softperience(dot)eu>
Subject: Re: 2nd Level Buffer Cache
Date: 2011-03-17 21:02:18
Message-ID: 4D82308A020000250003BA50@gw.wicourts.gov
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Rados*aw Smogura<rsmogura(at)softperience(dot)eu> wrote:

> I have implemented initial concept of 2nd level cache. Idea is to
> keep some segments of shared memory for special buffers (e.g.
> indices) to prevent overwrite those by other operations. I added
> those functionality to nbtree index scan.
>
> I tested this with doing index scan, seq read, drop system
> buffers, do index scan and in few places I saw performance
> improvements, but actually, I'm not sure if this was just "random"
> or intended improvement.

I've often wondered about this. In a database I developed back in
the '80s it was clearly a win to have a special cache for index
entries and other special pages closer to the database than the
general cache. A couple things have changed since the '80s (I mean,
besides my waistline and hair color), and PostgreSQL has many
differences from that other database, so I haven't been sure it
would help as much, but I have wondered.

I can't really look at this for a couple weeks, but I'm definitely
interested. I suggest that you add this to the next CommitFest as a
WIP patch, under the Performance category.

https://commitfest.postgresql.org/action/commitfest_view/open

> There is few places to optimize code as well, and patch need many
> work, but may you see it and give opinions?

For something like this it makes perfect sense to show "proof of
concept" before trying to cover everything.

-Kevin

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Alvaro Herrera 2011-03-17 21:22:10 FK constraints "NOT VALID" by default?
Previous Message Jesper Krogh 2011-03-17 20:02:58 Re: really lazy vacuums?